Madison, Wisconsin (CNN) -- After weeks of demonstrations in the state capital, Wisconsin Republicans cleared a final hurdle to a controversial proposal on Thursday after the state's Assembly passed an amended version of a bill that would curtail the bargaining rights of most state workers.

The vote was 53-42 in favor of the bill.

"I applaud all members of the Assembly for showing up, debating the legislation and participating in democracy," Gov. Scott Walker said in a written statement.

State Senate Republicans had approved the amended version Wednesday night, despite the absence of 14 Democratic senators who fled the state to prevent a necessary quorum of 20 votes.

The amended bill stripped the spending components out of the original proposal, enabling lawmakers to pass the measure with fewer votes.

Cries of "Shame, Shame, Shame!" filled the Capitol building following Thursday's vote. The bill will soon be delivered to Walker's desk, who is expected to sign the bill into law.

Meanwhile, at least one Senate Democrat said he has returned to his home state after spending weeks in Illinois in an effort to prevent the bill's passage.

Sen. Jim Holperin said the remaining 13 absentee Democrats will be returning individually between Thursday and Saturday.

But Democrat Sen. Kathleen Vinehout quickly disputed that assertion, claiming absentee lawmakers have remained in Illinois. She added that she did not know where Holperin was.

The weeks-long standoff reached a fever pitch Thursday after a spokesman for Republican Senate Majority Leader Scott Fitzgerald said the leader received two death threats, which detailed the ways in which the writer claimed Fitzgerald would be killed.

Both threats were e-mailed from the same address, said the majority leader's spokesman, Andrew Welhouse.

Meanwhile, throngs of protesters demonstrated outside the Capitol building, which police had earlier closed, forcibly removing those inside who refused to leave. The police later reopened one entrance.

"These arrogant actions are what I had a nightmare about last night," said Assembly Minority Leader Peter Barca, a Democrat, who called the lockout an "outrage."

The Assembly had convened Thursday afternoon to vote on the revised measure, which was left only with provisions taking away collective bargaining powers and increasing health insurance and pension fund contributions.

Placard-wielding demonstrators had blocked the building's entrances, chanting "Let us in!" as police struggled to keep order. But shortly before noon, lawmakers were able to access the building through the one open entrance.

The governor has defended the proposal as an integral measure that allows Wisconsin to avoid property tax hikes and public employee layoffs in an effort to balance the budget.

"It's about giving local government the tools they need to make reforms," he told reporters, saying it's part of an effort to address the state's impending $3.6 billion deficit.

While the proposal has a fiscal impact, he said, the new version of the bill does not have an appropriations component -- something that allowed Senate Republicans to approve the measure, despite the absence of Democratic senators.

Fourteen Democratic senators fled the state in mid-February to prevent the 20 votes necessary for a quorum on spending bills.

"The dirty trick is what those Democrats have played for the last three weeks," Walker said to critics' claims that the Senate had pulled a fast one.

Senate Democrats have called the bill an attack on the negotiating rights of state employees.

Barca filed a complaint with the Dane County District Attorney's office, claiming Wednesday night's committee hearing on the collective bargaining bill violated Wisconsin's Open Meetings Law.

"The state Senate and the state Assembly violated Wisconsin's very strict Open Meetings Law, by failing to give proper notice of their intended activities," said Lester Pines, an attorney for a teachers' union called Madison Teachers Incorporated. "When you act in violation of the law to pass a bill, the bill itself is void."

Nearly 200 protesters refused to leave the Capitol after the Senate vote, sleeping on the floor of the rotunda and in front of the Assembly doors. Capitol police had initially allowed the protesters to stay despite a court order that prohibits people from remaining inside the building at night.

"The Senate Democrats have had three weeks to debate this bill and were offered repeated opportunities to come home, which they refused," Walker said in an earlier statement on the vote. "In order to move the state forward, I applaud the Legislature's action today to stand up to the status quo and take a step in the right direction to balance the budget and reform government."

But the move drew howls of outrage from outside the chamber, where pro-union demonstrators again chanted "shame" and "you lied to Wisconsin" as the bill passed. Thousands more began to converge on the building, and a chorus of horns from passing cars echoed in the streets around the Capitol after the vote.

James Palmer, executive director of the Wisconsin Professional Police Association, said officers with the Madison police department and Dane County sheriff's deputies had been placed on alert ahead of Thursday's protests.

Walker and GOP lawmakers are trying to close a $137 million budget shortfall with a plan that calls for curbs on public employee union bargaining rights and requires public workers, with the exception of police and firefighters, to cover more of their retirement plans and health care premiums.

Public employee unions agreed to financial concessions that they say will help meet the state's fiscal needs, but Walker has said the limits on public bargaining are a critical component of his plan.

Raises would be capped to the rate of inflation, unless state voters approve. The legislation also would require unions to hold a new certification vote every year, and unions would no longer be allowed to collect dues from workers' paychecks.

Unions mobilized their supporters to oppose the bill, drawing tens of thousands of workers to rallies opposing Walker and supporting the fugitive Democrats.

Phil Neuenfeldt, president of the state AFL-CIO, said Wednesday night's maneuver "shows that Scott Walker and the Republicans have been lying throughout this entire process."

"None of the provisions that attacked workers' rights had anything to do with the budget," Neuenfeldt said.

But the Tea Party Express praised the developments, saying Walker was "holding strong" to his principles.

"Under tremendous pressure from union bosses, who have become irrelevant other than in their unquenchable thirst for power, Gov. Walker held fast and did what was best for the people of Wisconsin," a statement from the political action committee said.

The vote in the Senate on the amended measure was 18-1, with Republican state Sen. Dale Schultz -- who earlier had floated a compromise that neither side bought into -- the lone opponent.

Sen. Mark Miller, the Democratic Senate leader, said Republicans "conspired to take government away from the people."

"In 30 minutes, 18 state senators undid 50 years of civil rights in Wisconsin," Miller said in a statement condemning the vote. "Their disrespect for the people of Wisconsin and their rights is an outrage that will never be forgotten."